interface FromOracle : Type -> Type Decode a single Oracle value into an Idris type.
This interface is the typed counterpart to `ToOracleValue`.
It is responsible only for converting a single `OracleValue` into the requested Idris type.
Typical instances include:
- `String`
- `Double`
- `Bool`
- `ByteString`
- `OracleTimestamp`
- `OracleTimestampTZ`
- `OracleIntervalYM`
- `OracleIntervalDS`
This interface intentionally does not perform any row-level decoding, as that responsibility belongs to `FromRow`.
Example:
```idris
implementation FromOracle Double where
fromOracle (OracleNumber n) = Right n
fromOracle value =
Left $
MkOracleError
(-1)
("Expected NUMBER but got " ++ show value)
"FromOracle Double"
False
```
Parameters: a
Methods:
fromOracle : OracleValue -> Either OracleError a
fromOracle : FromOracle a => OracleValue -> Either OracleError a- Visibility: public export
interface ToRow : Type -> Type Convert an Idris record into a collection of named bind parameters.
This interface is intended for values that will be supplied to SQL statements as bind variables.
Each returned `BindParameter` associates a named placeholder (such as `:name`) with the Oracle value that should be sent to the database.
Unlike `FromOracle`, this interface operates on complete records rather than individual values.
Example:
```idris
implementation ToRow Person where
toRow person =
[ MkBindParameter ":name" (OracleString person.name)
, MkBindParameter ":age" (OracleNumber person.age)
]
```
The ordering of bind parameters is not significant when binding by name, but using the SQL declaration order is recommended for readability.
Parameters: a
Methods:
toRow : a -> List BindParameter
toRow : ToRow a => a -> List BindParameter- Visibility: public export
interface FromRow : Type -> Type Decode a complete database row into an Idris value.
A `FromRow` instance describes how an ordered list of `OracleValue`s returned by Oracle should be assembled into an application type.
Most implementations simply pattern-match on the expected row shape and delegate the decoding of each individual column to `FromOracle`.
Example:
```idris
implementation FromRow Person where
fromRow [name, age] = do
name' <- fromOracle name
age' <- fromOracle age
pure (MkPerson name' age')
fromRow row =
Left $
MkOracleError
(-1)
("Unexpected PERSON row: " ++ show row)
"Person.fromRow"
False
```
This interface is used by the typed query APIs (`query_`, `queryOne`, and `queryExactlyOne`) to transform raw query results into strongly typed Idris values.
Parameters: a
Methods:
fromRow : List OracleValue -> Either OracleError a
Implementations:
FromRow (List OracleValue)FromRow OracleValue
fromRow : FromRow a => List OracleValue -> Either OracleError a- Visibility: public export